Manufacturers of compost tumblers claim that you can make compost in 2 weeks. This sounds like a really good idea. Instead of waiting for months, you have almost instant compost. Are the claims really true? How labor intensive is the process? Is it worth using a compost tumbler?
Compost Tumblers – What are They?
A compost tumbler is some type of container that can be turned easily. It is usually some kind of plastic barrel. Compost matures faster if it is turned on a regular basis and compost tumblers are designed to make the turning process easy – you just turn the barrel.
The Science Behind Compost Tumblers
One of the reasons compost piles are slow is that the microbes do not get enough air. By mixing up the ingredients more frequently, more air is introduced and the composting process heats up and matures faster. This is certainly sound science.
The microbes need access to a nitrogen source which they get from the greens in the ingredients. The mixing process is better at mixing the greens and browns so they are next to each other. So the microbes decompose the browns quicker.
It is certainly true that mixing the ingredients regularly speeds up composting. But is the tumbler method any better than the compost pile, if both are turned frequently?
Compost Tumbler vs Compost Pile
Mother Earth News ran some comparison tests, comparing various brands of tumblers to compost piles. They concluded that “Under our environmental conditions, both the open (hot) pile control and the tumblers yielded rich, finished compost in about 10 weeks” (ref 1).
What is important to understand in this study is that the tumblers and the piles were turned at the same frequency. If you turn your compost pile regularly it will perform just as well as the compost tumblers.
Compost Tumblers Don’t Produce Compost in Two Weeks
Claims by manufacturers of producing compost in 2 weeks is highly exaggerated. The above study found it took 10 weeks.
It is quite possible that a compost tumbler will make compost faster than a pile because you will be more likely to turn the tumbler but it will NOT make compost in 2 weeks.
Pros and Cons of Compost Tumblers
Compost tumblers do have some benefits over conventional compost piles, but they also have some disadvantages.
- Turning is easier. Turning most tumblers is easier than turning a compost pile. If turning is easier you might do it more, and your compost will be ready faster.
- Fewer rodents. Since the tumbler is a closed system, rodents and other animals will not be a problem.
- Tidier. Some people feel it looks better. I don’t know – a big blue barrel is not exactly pretty!
- Produces less odors, provided that the ratio of greens to browns is correct.
- More Expensive. Hard to beat a pile on the ground when it comes to cost.
- Smaller. Tumblers are limited in size – piles can be any size and can change in size as needed.
- Moisture control is more difficult. Controlling moisture is more critical in a tumbler since it does not allow excess to leave as easily. This could be a benefit in dry climates.
- Control of browns and greens is more critical. Too much greens and the tumbler becomes a slimy mess.
Do Tumblers Require a Compost Accelerator?
Compost accelerators, compost starters and compost activators are recommended by many manufacturers of tumblers. I guess the idea is that the container is fairly closed, and that it is not in contact with soil. Seems to make sense that microbes would have a hard time finding the composting material, and so adding a commercial compost accelerator is recommended.
As reported in Compost Accelerators, Starters and Activators, the plant material going into a compost tumbler already has lots of microbes on it. Adding more is not required. If you feel the need, just add some old compost or soil and it will add lots of microbes. There is no need to buy compost accelerators.
DIY Compost Tumbler
The compost tumbler does have some advantages over compost piles, especially for smaller yards in urban environments. If you want to try one there are lots of DIY examples on the internet. Reference 2 has many different compost tumbler designs available.
Here is a simple design you might want to try:
1) Mother Earth news Tests Compost Tumblers: http://www.motherearthnews.com/nature-and-environment/testing-compost-tumblers-zmaz03amzgoe.aspx
2) Lots of plans for doing it yourself compost tumblers: http://piximggif.com/diy-compost-tumbler-plans
3) Good information About Compost Tumblers: http://eartheasy.com/compost_tumbler.htm
3) Photo Source: James Emery